1. Field of the Invention
The present invention relates to a magnetic head having a magnetic core and a slider for supporting the magnetic core, and more particularly to a magnetic head preferably used in a magnetic disc apparatus in which both sides of a flat circular magnetic recording medium; i.e., magnetic disc such as a floppy disc are supported by a pair of magnetic heads disposed to correspond to both sides of the magnetic disc in a manner that the magnetic heads perform recording and/or reproducing of information onto and/or from tracks on both different sides of the magnetic disc.
2. Description of the Prior Art
Known as this type of magnetic head is the catamaran type of magnetic head to be used in a magnetic disc apparatus for recording and/or reproducing information on and/or from a flexible magnetic recording medium, for instance, a magnetic disc such as a floppy disc.
A conventional arrangement of such a magnetic head will be explained with reference to FIGS. 1 and 2.
Reference numeral 9 in FIG. 1 denotes a resilient plate made of stainless steel or copper alloy which is fixed to the end portion of a supporting member mounted on a magnetic head carriage (not shown). A magnetic head 1 is mounted on this resilient plate 9. FIG. 1 shows only a portion of the magnetic head 1 which is on one side of the resilient plate 9 and which is confronted with the disc sliding surface, and the illustration and explanation of a portion mounted on the opposite side of the resilient plate 9 are omitted.
Reference numeral 2 in the arrangement of the magnetic head 1 denotes a recording and/or reproducing core in the form of a thin plate. A magnetic gap 2a is formed on the upper edge surface of the recording and/or reproducing core 2 which is confronted with the sliding surface. The recording and/or reproducing core 2 is sandwiched on both sides by reinforcing plates 10.
Furthermore, reference numerals 3 denote erasing cores in the form of a thin plate which have magnetic gaps 3a formed on the upper edge surfaces of the erasing cores 3 facing the sliding surface. A reinforcing plate 11 is sandwiched between the erasing cores 3.
The respective end edges of the erasing cores 3 are abutted against the end edges of the reinforcing plates 10 and are disposed in parallel with the recording and/or reproducing head 2. The end edge of the recording and/or reproducing core 2 is abutted against the end edge of the reinforcing plate 11.
Reference numerals 4 and 5 denote sliders formed from a non-magnetic material such as ceramic to support and reinforce both the cores 2 and 3. The sliders 4 and 5 ensure that both the cores 2 and 3 slide smoothly over the surface of the magnetic disc (not shown). These sliders 4 and 5 sandwich the reinforcing plates 10 on both sides of the recording and/or reproducing core 2 and the erasing cores 3.
The slider 4 is in the form of a rectangular thick plate having a sliding surface 7 in the same plane as the surfaces of the above-mentioned cores 2 and 3.
The other slider 5 is in the form of a block with a regular parallelepiped shape and having a greater width than the slider 4, and has a sliding surface 8 in the same plane as the surfaces of both the cores 2 and 3. A groove 6 is formed in this sliding surface 8 and is disposed on the side of the center a little toward the cores 2 and 3 in parallel with the cores 2 and 3. Stated another way, the slider 5 comprises a grooved surface 6 having lands definded by the sliding surfaces 7 and 8.
Further, the center of the groove 6 viewed from the direction indicated by the arrow is positioned in the center of the entire sliding surface of the magnetic head 1. Both of the cores 2 and 3 are disposed on one side of this central position (in this case, the right-hand side), so that the cores 2 and 3 on one side of a magnetic disc 12 are displaced from the cores 2 and 3 on the other side of the magnetic disc 12 by a track displacement A which is the distance between the positions of the same-numbered tracks on the respective sides of the magnetic disc 12, as illustrated in FIG. 2. Usually, the track displacement is equal to 4 or 8 track pitches.
The track displacement A is provided in order to prevent the generation of mutual interference, that is crosstalk, caused by leakage magnetic flux between the tracks corresponding to the recording and/or reproducing cores 2 and 2' on the magnetic heads 1 and 1' during recording and/or reproducing.
When recording and/or reproducing, the abovementioned magnetic head 1 and a magnetic head 1', having exactly the same structure as the magnetic head 1 and being inverted (since the magnetic head 1' has the same structure as the magnetic head 1, the reference numerals denoting common portions are distinguished by the addition of a prime "'"), sandwich the upper and lower surfaces of the magnetic disc 12 while this magnetic disc 12 is rotated.
In this fashion, the magnetic gaps in the recording and/or reproducing cores 2 and 2' and in the erasing cores 3 and 3' of the magnetic heads 1 and 1' respectively trace tracks at different positions on both the upper and lower surfaces of the disc 12, so that recording and/or reproducing, or erasing of information is performed.
As magnetic disc apparatus for performing higher-density recording on compact magnetic discs have been developed in recent years, the above-mentioned track displacement A has become narrower as shown in Table 1 below.
TABLE 1 ______________________________________ Track Density Track Displacement ______________________________________ 5-inch discs 96 TPI 2.117 mm 3-inch discs 100 TPI 2.032 mm 3.5-inch discs 135 TPI 1.505 mm ______________________________________
As shown in Table 1, the track displacement A in magnetic heads for use with 3.5-inch magnetic discs is particularly narrow.
As a result of this narrower track displacement, the above-mentioned crosstalk in this type of magnetic head is increased. For example, the level of crosstalk in magnetic heads for 5-inch floppy discs is 35 dB, but the level of crosstalk is increased to 25 dB in magnetic heads for 3.5-inch floppy discs.
Accordingly, there is a problem in conventional magnetic heads that recording and/or reproducing errors are likely to occur easily due to crosstalk between the magnetic cores corresponding to both sides of a magnetic disc.
Furthermore, there is another problem that this crosstalk impedes the making of compact magnetic discs and the realization of higher densities of recording and/or reproducing tracks and therefore it is difficult to provide a smallsized magnetic disc apparatus.